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By Nirmal Weerasekara, Lian X. Liu, The University of Queensland, Weiguo Xie, Benjamin Bonfils, Ping Yu

A mill model structure based on the population mass balance framework incorporating breakage characteristics, slurry and solids transport, product classification and discharge and energy consumption was reported in XXVII IMPC and named the Generic Tumbling Mill Model Structure Version I (GTMMS I). In this work, a new 4D (four dimensional) appearance function sub-model based on the experimental results of the JK Rotary Breakage Tester (JK RBT) was developed to describe the breakage characteristics and was applied to this new model structure. The newly developed 4D appearance function model has fewer fitting parameters and is more generic in nature. Most importantly, it is applicable to both high and low energy impact breakage. It is therefore much more versatile in comparison to the existing JKMRC t10- tn appearance function and the size-dependent JK M-p-q t10-tn appearance function. In addition, the Discrete Element Method (DEM) energy distribution model was integrated into the new model structure. With DEM results providing energy distribution information inside the mill directly, the selection function and the back-calculation method used in the existing JKSimMet modelling method are not needed in this model structure. With the above two revolutionary innovations, the previous model structure was upgraded to the Generic Tumbling Mill Model Structure Version II (GTMMS II). Furthermore, the new model structure is dynamic in nature with time-stepping technique for non-steady-state simulation. A case of the dynamic grinding of a SAG mill was studied to validate the GTMMS II. The model simulation results agreed well with the plant data. With the newly developed 4D appearance function model, the incorporation of DEM energy distribution and transport function, the GTMMS II is an important step forward towards mechanistic modelling of tumbling mills.

Jan 1, 2016

By R. W. Thompkins

"PREFACEPart 1 of this paper, published in the September issue, covered the occurrence of uranium, radiation from uranium ores, the uranium series, radioactive theory, radioactive equilibrium and application to the radon series, the working level, the theory of emanation and diffusion, transport by thermal diffusion of radon emanating from porous rocks, and definitions.This Part 2, which follows, deals with radiation theory applied to uranium ores, other radon migration factors, factors affecting the radon gas release rate, the measurement of radon gas emanation rates, the tunnel concept, variation of emanation rate with grade and estimating radioactivity from grade analysis.The series will conclude with Part 3, in the November issue, which will discuss the techniques for controlling radiation and provide some example calculations.10.0. Radiation Theory Applied to Uranium Ores10.0.1. The processes of diffusion transport of radon gas, through rock from the fundamental physics is a function o f the radon gas concentration in the interstitial pore spaces and the distance from the surface. Expressed by Fick's first law of diffusion, it is expressed: [ ]10.0.2. The maximum concentration is a function of the emanating power (ß), thus the above equation may be expressed: [ ]10.1. The Effect of Porosity10.1.1. If a constant emanating power is assumed (ß), a family of curves can be obtained for concentrations at varying distances and rock porosities. The curves as originally plotted assumed a constant emanating power of 5 x 10-4 pico curies/litre/sec and show the maximum expected concentrations in the pores in pico curies per litre. Because these concentrations are proportioned to the emanating power, this set of curves can be structured to show the fraction of maximum concentrations possible at various porosities of the rock.10.1.2. Notice that at 10, 20 and 30% porosities a 5-cm sample (hand-sized and drill-sized pieces) has no practical increase in pore concentration. Thus, by measuring the emanating power of hand-sized pieces of ore, the actual radon gas production into any pile of broken ore could be estimated readily."

Jan 1, 1982

By Yuki Tsunazawa, Shuji Owada, Sho Fukui, Chiharu Tokoro

"Since the amount of e-waste has been rapidly increasing all over the world, there is a desire to develop the effective recycling process. E-waste has various kinds of electronic components with valuable and/or hazardous materials. Recycling of them is an important subject from the viewpoint of both the recovery of valuable materials and waste treatment. In common with all mineral processing, the comminution of e-waste is a key process because the liberation states after comminution determine the overall efficiency of metal recovery. Since some of useful critical metals are concentrated in a specific component, a special and selective grinding is expected to be effective. However, the knowledge about the mechanism and the effectiveness of the selective grinding is still limited and unclear.To better comprehend the mechanism, in this study, the investigation of comminution process using the particle-based simulation was conducted. Especially, this study focused on the comminution performance of printed circuit boards (PCBs), which are major components of e-waste. The behavior of PCBs and airflow in a drum typed agitation mill having flexible chains was simulated by the discrete element method (DEM) coupled with computational fluid dynamics (CFD). To model the shape of PCBs, the particle based rigid body model was introduced into the DEM. Since this model could not directly simulate the breakage phenomena, collision energy was calculated to qualitatively evaluate the comminution performance. In addition, the simulation results were compared with the experimental comminution tests using simulant PCBs where some capacitors were solder-mounted. These results indicated that comminution performance was affected by the rotation speed of the agitator. It was also demonstrated that the comminution performance was qualitatively evaluated using the particle-based simulation and this particle-based simulation made it possible to investigate the mechanism of e-waste comminution."

Jan 1, 2016

By Andrew Bamber

The mining and beneficiation of minerals is the second largest end-use of electrical power on the planet, and comminution is by far the largest single contributor to this. Several jurisdictions, including British Columbia, have, in response to concerns about greenhouse gas emissions and climate change, adopted energy conservation legislation, including carbon taxes, carbon trading and conservation incentive schemes. Key to achieving conservation objectives is firstly an understanding of usage metrics across the various unit operations in the sector, and secondly an understanding of the conservation potential represented by available technologies and approaches in reducing end-use. This paper presents the results of a recent utility-funded study on energy use metrics and conservation potential at large open pit mines which are typical of the sector in BC.

Aug 1, 2013

By Davood Moradkhani, Maryam Rasouli

"The present study reports solvent extraction and separation of zinc from concentrated nickel sulfate solution. In our previous study, Zn and Cd in cold filter cake (CFC, 45-55% Zn, 11-16% Cd, and 2.5-4% Ni) were extracted by alkaline leaching followed by electrowinning processes respectively. The strip solution from electrowinning process, was a pregnant liquor solution (PLS) containing 16.8 g/l Ni and 4.2 g/l Zn. In this work, PLS is subjected to the solvent extraction process for separation of traces of Zn from high grade nickel. The zinc free raffinate containing 16.6 g/l Ni sulfate solution will flow to nickel electrowinning plant for cathode production. Di-(2-ethylhexyl) phosphoric acid (D2EHPA) is the organic phase used in this study. The effects of various parameters such as organic phase concentration (10- 40 % v/v), pH (1.5-3), and temperature (25 and 45°) are investigated. Zinc over nickel separation factor increases by increasing pH from1.5 to 3. The results show that 98.7% of Zn was loaded at25°C O/A ratio of 1, pH 3, and 10% vol. D2EHPA. A 10 M NaOH is used for pH control. However, replacement of pH controlling agent with ammonia solution (25%. v/v) results in interesting observations. Ammonia addition, reduces the solubility of Ni2+ cations in solution. Nickel starts to precipitate from raffinate in a crystalline bluish-green form. The obtained crystals are characterized by XRF and identified to be nickel-bearing analog of boussingaultite, a rare sulfate mineral of nickel with chemical formula of Ni (NH4)2(SO4)2.6H2O. The crystallization rate of crystals is studied. It is a slow precipitation process with 75% in 4 days.INTRODUCTION Annually, many hydrometallurgical processes such as electrowinning, solvent extraction and leaching are applied to waste filter cakes in Zanjan, Iran. These additional processes on filter cakes are critical from both environmental and economic points of view. CFC (cold filter cake) is a toxic but valuable filter cake (45-55% Zn, 11-16% Cd, 2.5-4% Ni, and 0.2-1.5% Cu) produced in many zinc production plants. Our research group at Research and Engineering Company for Non-ferrous Metals (ReCo.), developed a series of hydrometallurgical methods for extraction of zinc, cadmium and nickel from CFC (Moradkhani, & Rasouli 2012). The recovery of zinc and cadmium with alkaline leaching and electrowinning was successfully studied. The strip sulfate solution from cadmium electrowinning unit, contains high concentration of nickel with some traces of zinc impurity. This pregnant liquor solution (PLS) was analyzed and reported to contain 16.8 g/l Ni and 4.2 g/l Zn. In this work, PLS is subjected to the solvent extraction process to separate Zn from nickel (Fig. 1). The organic phase stripping solution containing 4.2 g/l zinc and 200 ppm nickel can be circulated and used in the acidic leaching step. This generates nickel solution with high purity suitable for nickel cathode production."

Jan 1, 2017

By Vincent Doyon

For several years, the GDD SSW EM Probe is being used in nickel?s mines in Canada and Brazil to define ore limits, reduce dilution and predict nickel grades. It is used with success to test most if not all percussion blast holes at all Falconbridge Mines in Sudbury and Raglan and all Inco?s Thompson mines. However, after testing the SSW Probe in other metal mines, we realized that EM conductivity does not define ore limits by testing blast holes for copper, zinc or gold. For non-conductive ores, no instrumentation is yet available on the market to reduce dilution, by outlining quickly and inexpensively the real shape of an orebody. To that effect, Instrumentation GDD Inc has developed a new revolutionary photonic probe that will make the reduction of dilution possible by probing blast holes. Once surveyed with the probe, a computer draws graphs of the ore grade as a function of depth for each blast hole. A contribution by Canada Economic Development made possible the development of this new technology. Canmet and Soredem also cautioned this technology developed by Instrumentation GDD Inc. This new photonic probe will allow: 1) to better understand the shape of the orebody 2) to raise the grade of the ore fed to the mill 3) a more complete extraction of the ore 4) to raise the competitiveness of mines

Oct 1, 2004

By Ali M. Ghazi, Ronald J. Goble, Lowell S. Whiteside

"Geerite (Cu1.6S) is a rhombohedral copper sulphide which occurs naturally in epitactic replacement of sphalerite; cell dimensions closely approximate those of the host sphalerite.Geerite-type structures can be produced by leaching digenite (Cu1.8S) in ferric sulphate solutions. X -ray diffract ion and electron microprobe studies indicate that eight metastable geeritetype structures can be produced, depending upon the concentration of f erric sulphate solution used and the duration of the each. Although compositions cluster on or near values observed for natural phases, optical properties indicate that we are dealing with polymorphs of these phases. Leaching of chalcocite (CU2Sj in dilute f erric sulphate solutions produces similar results. In contrast, leaching of chalcocite in more concentrated solutions seems to produce true analogues of natural minerals.During froth flotation, sphalerite is activated with a monolayer of floatable copper sulphide with the composition, CuS, of the mineral covellite. However, covellite is not significantly more floatable than sphalerite, and has an incompatible structure because of the presence of covalently-bonded atoms of sulphur. Leaching ofdigenite was used to produce a polymorph of covellite with a geerite-type structure, compatible with that of sphalerite. This polymorph has a flotational behaviour similar to copper-activated sphalerite, suggesting that the monolayer has a geerite-type CuS structure. IntroductionIn an ideal close-packed sulphide structure the distance between sulphur layers, D, is equal to 2R 2/3, where R is the radius of the sulphur atoms. In sulphides with covalently-bonded sulphur layers, such as covellite (Fig. I), D will be an average of the number of covalentl y-bonded and close-packed sulphur layers, weighted as to the relative number of each type of layer. Both D and R are spacings which are readily identifiable structurally and on X-ray diffraction patterns. Goblel has shown that for copper-iron sulphides with metal-to-sulphur ratios between 0 and 2 and copper-to-total metal ratio s between 113 and I there are strong correlations between composition and measured D and R distances (Fig. 2). D can be represented by a single empirical equation relating interlayer spacing to composition; R must be represented by three equations relating the radius of sulphur atoms to composition. One of these equations (R, in Fig. 2) represents ideal close-packed behaviour, the other two represent sulphur radii greater than (R1) or less than (Rh) the ideal."

Jan 1, 1988

By F. T. Manns, G. Harper

"The Swayze gold mine is an Archean vein deposit in northern Ontario. The veins are superimposed on a conjugate joint system and are contained within an anastomosing alteration envelope in a metadiorite body. Reserves were estimated on the basis of fire assays of channel samples and car load samples from underground mine openings, surface and underground diamond drilling and surface trenching. A semi-variogram constructed from channel samples along one of the drifts yielded a horizontal, regionalized influence of approximately 9.0 m. Common industry practice has been to use 6.1 m for similar deposits in Ontario. Proven ore was defined from underground openings. The maximum extrapolation distance for proven ore along strike and dip from a data point is taken to be 6.1 m. Probable ore is extrapolated 7.6 m from a data point in a mine opening or from a drill intersection. Possible mineralization is based on geological continuity one-half the distance to a neighbouring data point.The mineral inventory estimate of 1.45 million tonnes at a grade of4.8 g Au/tonne gives an excellent outline of the geology of the deposit. The deposit contains 313 000 tonnes of ore reservesat a fully diluted grade of6.9 g Au/tonne. These figures include dilution for several reasons: (I) a 2.1 m mining width is used rather than the more typical 1.5 m width to allow for over break because of the shallow dip of some vein zones; (2) over break is allowed for adjacent to major unmineralized dykes; and (3) grams of gold are deleted from estimates to allow for the mining of unavoidable minor dykes.A personal computer with off-the-shelf software was used to compile 712 geologically defined ore blocks and sort them into a number of revealing categories. The computer was used to perform grade sensitivity tests, as well as to evaluate depth potential. Hopefully, the reiterative aspect of the method has randomized the errors and helped to cancel their effects."

Jan 1, 1987

By Lanny Pasternak

"This article is directed at plant production, engineering and maintenance personnel. Seldom does any industrial operation take the time to study the costs involved in the generation of what is probably their most expensive plant utility energy source.IntroductionIn the typical industrial plant in Canada, a 200 hp, 900 cfm, air compressor costs about $60,000* per year to operate (Fig. 1). In 1989 when BC Hydro embarked on their industrial energy management program Airflow Energy Ltd. were asked to spearhead the “Efficiency Compressed Air” portion of that program with a mandate to perform onsite overview surveys and physical hands-on testing of some 300 selected industrial plants throughout British Columbia for compressor efficiencies and wasteful air leaks (Fig. 2). The program duration lasted until 1995, during which time a tremendous amount of data were amassed relating to equipment types, clients’ operating habits, end-use applications and operating costs.During the past six years, Airflow Energy also performed somewhat similar surveys but on a smaller scale in Alberta, Ontario, the United States and the Republic of China. It was no surprise to find some inherent equipment concerns related to efficiency as well as neglected energy wasteful air leaks, so British Columbia was not alone and the problems appear somewhat universal."

Jan 1, 1996

By Isabel F. Barton, J. Brent Hiskey

Chalcopyrite (CuFeS2) is the earth’s most abundant copper ore mineral, but is refractory to leaching with sulfates, chlorides, and other common lixiviants and oxidants. This has led to increasing research into alternative lixiviants for recovering Cu from chalcopyrite. Here, we review the leach kinetics of chalcopyrite in glycine, ionic liquids, and methanesulfonic acid, compared to baseline ferric sulfate and ferric chloride. Glycine (CH2NH2COOH) has long been used in applications such as biocatalysis and electroplating, and has recently been examined as a lixiviant for whole ores and concentrates of both copper and gold. It is nontoxic, biodegradable, and capable of strongly complexing Cu2+. Compatible oxidants are peroxide, dissolved oxygen, and ferric sulfate. Chalcopyrite leaching rate in glycine is chemical reaction-controlled, but the effects of grain size and the reaction orders with respect to lixiviant and oxidant concentrations and mass transfer vary. The use of ionic liquids as a leaching agent for chalcopyrite has been extensively investigated in recent years. This system is based primarily on the use of the imidazolium molecule (C3H5N2), which is a planar 5-member ring structure. This lixiviant has been applied to the leaching of chalcopyrite in the form of pure mineral, concentrates, and ores. Kinetics of ionic liquid leaching of chalcopyrite vary substantially depending on the type and concentration of ionic liquid. Methanesulfonic acid (HCH3SO3) is one of the newest lixiviants available in leaching, having only been examined in the last decade. It has been examined as a substitute for sulfuric acid, since it is less corrosive, is biodegradable, and breaks down to carbon dioxide and sulfate over time. The rate of copper leaching from chalcopyrite by methanesulfonic acid is controlled by diffusion and exhibits a strong dependence on oxidant type and concentration. Despite promising reaction rates and total extraction by some of these novel lixiviants, comparison with baseline ferric sulfate and ferric chloride systems makes it doubtful that any will be commercially viable in the near term. Only at very high reagent concentrations and temperatures, and/or very fine grain size, did any of the systems perform comparably to the much cheaper ferric chloride at extracting Cu from chalcopyrite. Most had similar overall reaction rates and total extraction to ferric sulfate, which is relatively common and cheap. However, the leaching kinetics of these novel lixiviants offer valuable insight into the dissolution behavior of chalcopyrite in various systems.

Jan 1, 2019

By R. Shamsodini, A. Poor Zaeif Doost, H. Haji Amin Shirazi, M. R. Garmsiri

"With columns being installed in rougher section at Miduk Copper Complex, the rougher feed mainly reports to rougher-scavenger cells. To evaluate the efficiency of regrinding circuit, we conducted flotation experiments on samples of the feed and the products of the regrinding circuit. The grade difference of these products at 85% recovery was considered as the efficiency index. Results show that, with weight recovery of the rougher-scavengers the efficiency of the circuit increases. Exclusion of the rougher-scavenger concentrate from the feed to the regrinding circuit, resulted in an increase in the efficiency index from 10.12 to 17.6%.INTRODUCTIONThe flotation circuit at Miduk Copper Complex consists of five flotation columns as roughers and ten mechanical cells as rougher-scavengers. According to design criteria, 75% of the final product was expected to be produced by the rougher columns, while most of the feed consisting of liberated valuable particles is introduced into rougher-scavengers. To liberate locked particles, the rougher-scavengers concentrate is introduced into the regrinding circuit (see Figure 1 below). The regrind mill is in reversed closed circuit with a secondary hydrocyclones cluster, and the cyclone overflow is introduced into three parallel cleaner columns. Cleaners concentrate reports to concentrate thickener and the column tailings is introduced into six mechanical cleaner-scavenger cells. The cleaner-scavengers concentrate reports to the regrind circuit(Figure 1)."

Jan 1, 2012

By Peter J. Franklin

"Short-term mine planning of open pits is an activity that has historically been carried out by hand. Typically, the use of computers has played little part in this type of mine planning. This paper describes the objectives and the procedures involved in short-term mine planning, comments on the type of computer systems available, and describes in detail a computer-aided short-term planning and scheduling system known as STEPS.IntroductionThe mine planning department of any o pen-pit mining operation performs a wide variety of different tasks. However, their primary concern is the preparation of detailed long-and short-term mine plans. These mine plan s will define the long-term operating strategies and definitive everyday working plan s for the ongoing development of the open pit.In this day and age, when operating costs have spiralled upwards due to inflation , and product revenues have decreased due to depressed economies and poor markets, it is vitally important for all aspects of the mining operation, including mine planning, to be efficient and cost effective.There are numerous options available for planning engineers when generating a mine plan. A cost effective mine plan must investigate all these options and select the optimum. When using manual planning techniques, it is often impossible to evaluate all the available options. To do this, and to produce an optimum mine plan, a computer is required.This paper discusses mine planning, with emphasis toward the short-term plan and comments on how the processes may be computerized. It also describes in detail, a computer software system called STEPS, which has been designed as an interactive graphics, computer-aided short -term mine planning and scheduling tool."

Jan 1, 1985

By Yan Germain, Université Laval, Bernard Dallaire, Jocelyn Bouchard, Peter Radziszewski, Gilles LeBlanc, Michelle Levesque, Nicolas Tremblay

"The comminution process is estimated to be only 1% efficient, resulting in waste energy dissipated as heat, noise, and vibration. Energy recovery from grinding circuits has not been implemented mainly because recovering heat from the surface of the grinding mill or from mill slurry can impede operation, increase maintenance requirements, and prolong plant shutdown time (and production). However, currently very little information is available in the public domain regarding the amount of waste energy and that potentially recoverable in the grinding circuit of a mineral processing plant. Availability of such information could drive innovation and improve decision-making regarding opportunities for waste energy recovery. The Canadian Mining Innovation Council (CMIC) has initiated a study with CanmetMINING and mining industry partners to develop a model to map the energy flows in grinding circuits and to quantify the potential for energy recovery. The paper outlines the underlying fundamentals and data requirements for use in the model and then focuses on quantifying the energy recovery potential of the semi-autogenous grinding and ball mill circuits at the Agnico Eagle Goldex Division. Results show that most of the electrical energy (over 75%) is used to heat the slurry, leaving only a relatively small amount of it to achieve mechanical work (~9%). INTRODUCTIONCanmetMINING commissioned a study in 2013 to better understand the barriers for adoption of new technologies in the mining industry (MNP, 2013). The conclusions highlighted the importance of enhancing industry/regulator engagement and communication to raise awareness and improve the industry’s comfort level with new technologies.In November 2014, the Green Mining Innovation Advisory Committee (GMIAC) held a workshop to explore the possibility of accelerating the uptake of green mining technologies by bringing together key stakeholders among the mining value chain to address industry priorities. Participants included representatives from mining companies and associations, academia, provincial governments and federal departments and organizations. Two key priority areas emerged at the workshop: i) energy saving, and ii) water management."

Jan 1, 2016

By W. L. Dam

Grand Junction, Colorado’s legacy with uranium mining and milling serves as a model attracting international interest. Access to water and central location to carnotite ore containing uranium and vanadium resulted in the World War II military creating a site in Grand Junction for developing extraction techniques; subsequently, several commercial mill sites were built in the area. Uranium mills produced ore into the 1970’s as well as tonnes of radioactive waste tailings. Tailings contain radium that emits radon gas. Despite the radiation hazard, sandy tailings were added to concrete and became incorporated into roads, schools, businesses and homes. Clean up of sites containing tailings and mill sites began in the 1970’s involving city, state, and federal officials. The Climax mill site had become an auto junk yard mixed with mill tailings. A new disposal site was built out of town and away from the river in the 1990’s. After Climax mill tailings were removed to the disposal site, the land sat vacant for two decades until citizens and city officials developed a masterplan for the riverfront property. The Las Colonias river park is being built in stages including an amphitheater, gardens, businesses and parks. One of the biggest obstacles to site remediation and reuse was overcoming public outrage, fear, and lack of trust which made funding sources scarce.

Jan 1, 2020

By L. R. Bower

"This paper describes a highly versatile variable speed unit with a torque multiplication feature as a direct replacement for a fluid coupling .The unit is comprised of a modulating clutch with torque converter and lock-up options.The UCD does not start or stop the motor. This is carried out in the normal manner.The UCD continually monitors and rapidly regulates the output speed to the requirement of a set point demand from input signals or a pre-set program with full manual override.The pre-set program can include start and stop ramps, top speed and minimum speed regulation and also mid-speed set point with security for man-riding, etc. Speed variation is from zero to 100% on a constant duty basis.The input signals can be from any source, e.g. belt weigher. load profile bunker probes, mine monitoring system, etc.The UCD when fitted with a torque converter has a torque multiplication feature which automatically provides a starting torque up to two and a half times greater than the full load torque without exceeding the normal motor power levels.IntroductionIt is common practice in the mining industry to drive conveyors, whether they be belt or chain, through a transmission system incorporating a fluid coupling between the driving motor and gear-box .However, there are drawbacks and in an effort to attain a better degree of drive and control, two-speed motors - inverters cycle- converters - hydrostatic drives, etc ., have been introduced."

Jan 1, 1986

By D. Milne, G. Snell

"A new method to predict stope hangingwall failure in underground excavations is proposed. This method compares movement rate for stope hangingwalls, determined from changes in strain or deformation, with changing opening geometry. This geometry is represented by the effective radius factor (ERF), a measure of relative distance to supporting abutments from an opening surface point. This strain-ERF (SERF) approach is applied to an instrumentation program for Brunswick mine near Bathurst, New Brunswick. The SERF method for this case study predicted failure at an ERF of 13.9 m and hangingwall failure actually occurred at an approximate ERF of 12.4 m.RÉSUMÉ Cet article propose une nouvelle méthode permettant de prévoir la rupture de l’éponte supérieure des chambres d’abattage dans les excavations souterraines. Cette méthode compare la vitesse de mouvement des épontes supérieures des chambres d’abattage, déterminée à partir des changements aux niveaux des contraintes ou de la déformation, à la géométrie variable de l’ouverture au jour. Cette géométrie est représentée par le facteur du rayon effectif (ERF, de l’anglais Effective Radius Factor), une mesure de la distance relative jusqu’aux appuis latéraux de soutènement à partir d’un point de la surface d’ouverture au jour. Cette approche contraintes-ERF (SERF, de l’anglais strain-ERF) est appliquée à un programme d’instrumentation pour la mine Brunswick située près de Bathurst, dans le Nouveau-Brunswick. Pour cette étude de cas, la méthode SERF prévoyait une rupture à un ERF de 13,9 mètres (m); la rupture de l’éponte supérieure s’est effectivement produite à un ERF d’environ 12,4 m.INTRODUCTIONUnderground stope design can be improved with the installation of field instrumentation. The most commonly used instrumentation for monitoring rock mass behaviour around open stopes is extensometers. The y-axis of Figure 1 represents how the changing rate of movement, measured using either displacement- or stress-type instruments, can be observed over time. The magnitude of movement measured by extensometers can give an approximation of the load on installed support (Milne, Pakalnis, & Lunder, 1996) and a changing rate of movement can indicate approaching instability."

Jan 1, 2018

By Finley A. Campbell

"Nickel-copper sulphide deposits associated with basic rocks in the Quill Greek area and the White River area in the Yukon Territory have been studied and compared from the view-point of their general geology, structural geology, and the mineralogy of the ores. The relative amounts of the major constituents, magnesium, iron and calcium, and the minor constituents, nickel, cobalt and chromium have been determined spectrographically for two cross sections of the basic rocks at Quill Creek and one at White River. These data, along with petrologic and field evidence, were used to determine the sill and dyke-like character and nature of the basic intrusions. Loss on ignition is employed as a measure of the degree of serpentinization. The distribution determined shows that the serpentinization does not appear to have greatly influenced the inferred original distribution and lithophile associations of magnesium and nickel. The cobalt content may have been altered.The nickel content of the serpentinized peridotites ranges from an average of 0.36 per cent in one section to an average of 0.24 per cent in each of the other two sections studied. The cobalt averages 0.0038 per cent in the samples from the two Quill Creek sections and averages 0.0042 per cent at White River. These results have been compared with other available data.The sulphide ores are later than both the peridotite and gabbroic rocks and may be co-magmatic with them. There is no evidence in these areas to support an origin by lateral secretion; on the contrary, the alteration associated with the ores, the mineralogy and spatial relationship to basic and ultrabasic rocks, indicate the ores are derived from a basic magma."

Jan 1, 1960

By S. L. Gertsman

Canadian steel foundry practice has made marked progress during the past decade. Equipment suppliers, development engineers, and foundry personnel have focussed their attention on every phase of the foundry operation, with a resulting lower demand on manpower and materials. Also, more rigid specification requirements as to dimensional tolerances and quality have necessitated improvement and increased control at every stage from the pattern shop to the cleaning room. The growing trend toward mechanization is clearly evident. Equipment such as sand mixers, sand reclamation systems, material handling devices, moulding machines, core blowers, etc., is being increasingly employed by the steel foundryman. This equipment not only increases production but also tends to lessen the human variable so prevalent and disconcerting in the early days of steel founding. The result has been an improved and more reliable steel casting, which is gradually obtaining wider acceptance by design engineers. The purpose of this paper is to discuss briefly some of the practices being used, and also the direction of development that is being pursued by Canadian steel foundrymen.

Jan 1, 1948

By D. Thibault, A. Akhiate, M. Brochu, E. Braud

Cast martensitic stainless steels, 13%Cr-4%Ni, having carbon contents between 0.018 wt% and 0.067 wt% were normalized, air quenched, and tempered at two different temperatures (550°C and 610°C). Their microstructures were characterized by optical microscopy and X-ray diffraction (XRD). Macro and microhardness, tensile strengths, and impact resistance were quantified for each material and condition. Results show that the prior-austenite grain size is constant through the materials but the percentage of reformed austenite, contained in the martensitic matrix, depends strongly on the material chemistry and on the tempering temperature and on its duration. It is observed that, independently of tempering conditions, an increase in carbon content increases the material hardness and tensile strengths, whereas the elongation remains constant. In contrast, the results of Charpy type impact toughness tests show a different trend. The material containing the average carbon content (0.034 wt%) is significantly tougher than the two other alloys. Surprisingly, the toughness of the steel containing 0.034 wt% carbon was found independent of the reformed austenite content. It is thus concluded that carbon and reformed austenite contents are not the only parameters affecting the toughness of these steels.

Jan 1, 2014

By Jacque Turgeon, Gontran Foy

"The Mineral Research Centre of the Quebec Department of Energy and Resources has worked extensively on the development of a dry process to extract pure mica flakes from a phlogopite ore. The liberation of mica from the gangue is effected basically by impact crushing, and the ground ore is screened into several fractions, each having a fairly narrow range of grain size. Each sized fraction is then fed to an air separator where heavy grains are separated from light flaky grains. Heavy fractions are returned to hammer mills where gangue minerals are ground finer and blocky mica particles are exfoliated. A second stage of screening is performed and each fraction is sent to an air separator. This sequence is repeated until mica products are virtually free of gangue. These different fractions are then treated in a cage mill in which mica flakes undergo a more orderly exfoliation along cleavage planes. The ground mica is again submitted to a final screening stage, after which each fraction constitutes a final commercial product.This process permits the recovery of about 70% of the mica contained in the ore. The over-all process will be described along with technical details of each unit operation. Recent work on a wet grinding method to produce very fine mica will also be discussed.IntroductionRecords of production of mica in Quebec date back to 1886. Production has been more or less continuous since that time, with peak activity during the war years. Production was interrupted in 1966, but started again in 1972 when Marietta Resources and Laviolette Mining and Metallurgical Corporation started their joint operation in Canton Suzor, northwestern Quebec. Mica deposits of more or less importance exist in different parts of Quebec, of which three have attracted attention in recent years: the Canton Suzor deposit, the Canton Lamy deposit and the Canton Chasseur deposit. The Suzor orebody was first identified by Carl Faesler in 1936, who described the rock as ""brown biotite in flakes half an inch in diameter, with interstitial augite, apatite and feldspar""."

Jan 1, 1982